Drive system for food slicing machine

ABSTRACT

A drive system for driving the workpiece-retaining carriage of a food slicing machine, including a drive pulley rotatably driven by a servomotor in alternating, opposite directions. Opposite ends of a drive belt extend around the drive pulley through a gap between two idle pulleys. The drive belt seats against the idle pulleys and the opposite ends extend in opposite directions on the opposite side of the gap. The upper drive belt end extends over the curved surface of a support panel to gripping engagement of a tensioning pulley and clamp. The lower drive belt end extends over the curved surface of the support panel to gripping engagement of a second tensioning pulley and clamp. The support panel is mounted on a drive member that is, at its opposite end, rotatably mounted to a pivot, and rigidly mounted to the workpiece-retaining carriage.

This application claims the benefit of provisional application Ser. No.60/105,766 filed Oct. 27, 1998.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to drive systems, and more particularly to drivesystems for food slicing machines in which a food product retainingcarriage is reciprocatingly driven.

2. Description of the Related Art

In conventional food slicing machines, a workpiece-retaining carriage isreciprocatingly driven for the purpose of reciprocating a food productworkpiece, such as a cheese log, through a cutter. The workpiece is cut,forming a slice that falls downwardly due to gravity onto a conveyor, atray or another food product, such as a slice of bread or pizza crust.After the slice is formed, the workpiece is driven back across thecutter, dropping downwardly so that another slice can be formed. Theoperation of the slicing machine is cyclical, with a cutting strokeduring the first half of the cycle and the return stroke in the secondhalf of the cycle.

The workpiece-retaining carriage is linked to a drive mechanism.Conventional drive mechanisms are hydraulic rams, and cranks connectedto rotary motors, both of which are described in U.S. Pat. No.4,436,012. Both of these drive mechanisms mount to theworkpiece-retaining carriage near where the food product is retained.This configuration has the disadvantage that drive system parts andlubricants must be made of food grade materials, and must be washable bythe means used to wash the carriage.

The displacement of the carriage by the rotary motor and crank mechanismapproximates sinusoidal motion. This sinusoidal motion has largevariations in the speed of the workpiece during the formation of slices.These large variations result in inaccuracies in the formed slices.

Additionally, the width of the motor and crank mechanism is greater thanthe width of the carriage. This configuration makes placing multiplecarriages in a close, side-by-side relationship unfeasible.

Therefore, the need exists for a carriage drive system that can beadjusted to control the accuracy of formed slices. The drive systemshould also be mounted in a position that keeps moving parts away fromthe region of the food product workpiece to avoid the necessity ofexpensive materials and frequent washing. Furthermore, the drive systemshould be narrow enough that several carriages can be mounted in closeproximity without interference between moving parts.

SUMMARY OF THE INVENTION

The invention is an improved drive system for a food product slicingmachine. The slicing machine with which the drive system cooperates hasa frame, and a workpiece-retaining carriage attached to the frame. Thecarriage retains a food product workpiece therein, and reciprocates theworkpiece through a path including a cutter.

The drive system includes a drive member pivotably mounted to themachine frame about a pivot, such as a pivot pin. A support panel mountsto the drive member, and has a curved surface spaced from the axis. Thisspace is substantially equal to a radius of curvature of the curvedsurface. The curved surface has first and second sides.

First and second idle pulleys are connected to the machine frame, withthe second idle pulley spaced from the first, forming a gap. A drivepulley is drivingly linked to a rotatably driven shaft of a prime mover,preferably through a gear mechanism. An elongated, flexible drive means,preferably a belt, loops around the drive and idle pulleys. The firstend of the drive belt extends from attachment to the drive member, nearthe first side of the support panel's curved surface. The belt extendsthrough the gap between the first and second idle pulleys, around thedrive pulley, and through the gap. The second end attaches to the drivemember near the second side of the support panel's curved surface.

When the prime mover's shaft rotates in one direction, the drive belt isdriven in the same direction, applying a force to one side of thesupport panel and drive member. The drive member is displaced in onedirection, pivoting about the pivot axis and swinging theworkpiece-retaining carriage through an arcuate path. Upon reaching itsextreme, the prime mover stops the drive shaft's rotation and reversesits direction, thereby swinging the workpiece-retaining carriage throughthe arcuate path in the opposite direction.

By continuously reversing the prime-mover's direction of rotation, theworkpiece-retaining carriage is reciprocated through the arcuate path,thereby reciprocating a food product workpiece retained within thecarriage through a cutting blade, forming slices. The prime moverprovides a much more consistent velocity during cutting, which resultsin consistent slice thickness and spacing of multiple slices.Furthermore, because of the configuration of the drive system, severalworkpiece-retaining carriages can be mounted in a small space.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view illustrating the present invention.

FIG. 2 is a view in perspective illustrating a portion of the presentinvention, and its mounting position on the slicing machine.

FIG. 3 is a side view in section illustrating the preferred tensioningpulleys and adjustment mechanisms.

FIG. 4 is a side view illustrating the present invention.

FIG. 5 is a top view illustrating the present invention.

In describing the preferred embodiment of the invention which isillustrated in the drawings, specific terminology will be resorted tofor the sake of clarity. However, it is not intended that the inventionbe limited to the specific terms so selected and it is to be understoodthat each specific term includes all technical equivalents which operatein a similar manner to accomplish a similar purpose. For example, theword connected or terms similar thereto are often used. They are notlimited to direct connection but include connection through otherelements where such connection is recognized as being equivalent bythose skilled in the art.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment is shown in FIGS. 1 and 2, in which aworkpiece-retaining carriage, preferably the cluster box 12, isrotatably mounted to the frame 10 of the food product slicing machine14. The frame 10 encompasses many, but not all, regions of the machine14, and includes any of the structural components that make up the base,backbone or housing of the machine 14 (shown in FIG. 2). The machine 14includes the frame 10, and all other parts connected to the frame 10.

The cluster box 12 is, in its operable position, inserted into one ofthe chambers formed between the panels 8, which are part of the frame10. The cluster box 12 is rigidly mounted to the pivot shafts 16, andthe pivot bushings 17 are mounted between the pivot shafts 16 and thepanels 8. The cluster box 12 is driven in a pendulum motion about thepivot shafts 16, and the food workpiece, which could be one food log orseveral food logs as shown in FIG. 5, is retainer in the cluster box 12,protruding from the lower end where slices are formed in the foodslicing area 6 shown in FIG. 4.

The drive member 20 is rigidly mounted to the cluster box 12 at thepivot shafts 16, permitting simultaneous oscillating rotation of thedrive member 20 and the attached cluster box 12 about the axis of thepivot shafts 16. The drive member 20 is driven upwardly and downwardlyin reciprocating motion about the pivot shafts 16 as described below,and this motion drives the cluster box 12 in its slicing reciprocation.

The support panel 22 is rigidly mounted to the end of the drive memberthat is preferably farthest from the pivot shafts 16. The curved surface24 of the support panel 22 faces away from the pivot shafts 16, and hasa radius of curvature, R, substantially equal to the distance betweenthe curved surface 24 and the axis of the pivot shafts 16. The radius,R, is preferably between about 12 and 18 inches, but could be larger orsmaller. Generally, a larger radius, R, permits greater precision inmoving the cluster box 12.

A prime mover, preferably, but not necessarily, the servomotor and gearbox 30 is mounted to the frame 10 at a point spaced from the pivot shaft16. The drive pulley 32 is connected to the gear box, which attaches tothe drive shaft of the servomotor, preferably by directly mountingthereto, but alternatively connecting through any conventional linkage.The drive pulley 32 preferably has teeth formed in its outer,circumferential surface for inserting between, and engaging, thecorresponding teeth on the inner surface of the drive belt 34, which ispreferably a toothed timing belt. The preferred drive belt 34 could besubstituted by any conventional flexible, or hinged, means, such as adrive chain or rope, as long as the cooperating structures accommodateit.

The drive belt 34 extends around the drive pulley 32 into a gap betweenfirst and second idle pulleys 40 and 42. The idle pulleys 40 and 42 arerotatably mounted to the frame 10 between the support panel 22 and thedrive pulley 32. A gap is formed between the closest parts of the outercircumferential surfaces of the idle pulleys. The idle pulleys guide theopposing ends of the drive belt 34, that extend through the gap inopposite directions, toward opposite sides of the support panel 22. Thesurfaces of the segments of the drive belt 34 that extend between theidle pulleys and the support panel 22 seat against the curved surface 24of the support panel 22.

Tensioning pulleys 44 and 46 are mounted at opposite sides of thesupport panel 22 for grippingly engaging the toothed surfaces of theopposing ends of the drive belt 34 between the tensioning pulleys 44 and46 and the clamps 48 and 50.

From one end to the other, therefore, the drive belt 34 extends fromgripping engagement between the tensioning pulley 44 and the clamp 48,seating against the upper side of the curved surface 24 of the supportpanel 22, and into the gap between the idle pulleys 40 and 42. The drivebelt seats against the circumferential surface of the idle pulley 40 andspans the distance to the drive pulley 32, around which the drive belt34 extends. From the drive pulley 32, the drive belt extends thedistance back through the gap between the idle pulleys, seating againstthe idle pulley 42. The drive belt extends from the idle pulley 42 tothe curved surface 24 and seats against it, extending along it toclamping engagement between the tensioning pulley 46 and the clamp 50.Of course, the drive belt 34 could be an endless loop that, instead ofattaching at opposite sides of the support panel 22, attaches at onepoint at or between the tensioning pulleys 44 or 46.

During operation, the servomotor and gear box 30 apply a rotary force tothe drive pulley 32 in one direction. A tensile force is thus applied toone end of the drive belt 34 by the drive pulley. This tensile force isapplied through the drive belt to one of the tensioning pulleys grippingthe belt at one side, for example the tensioning pulley 44 on the topside, of the belt support panel 22. The tensile force applied to the endof the belt support panel rotates the drive member 20 around the pivotshafts 16, rotating the attached cluster box 12 in one half of thecutting cycle, which is to the left in the example and as shown in FIG.1.

Once the cluster box 12 is displaced a predetermined distance to theleft, the servomotor and gear box 30 rapidly stops rotating the drivepulley. The drive pulley is then driven in the opposite direction. Thedrive pulley 32 applies a tensile force to the opposite end of the belt,thereby applying a tensile force to the opposite side, for example thetensioning pulley 46 on the lower side, of the belt support panel 22.This produces an upwardly directed force that displaces the cluster box12 in the opposite direction for the other half of the cutting cycle,which is to the right in the example and as shown in FIG. 1.

The length of the stroke the cluster box 12 is driven through iscontrolled by the servomotor. The degree of rotation of the servomotor'sdrive shaft determines the distance the drive member 20 is displaced,and therefore the distance the cluster box 12 is displaced. A centersensor, which is not shown, detects the center point of the stroke, andsignals a central computer of the presence of the cluster box 12 at thecenter point. This sensor is used to calibrate the system, so that theservomotor's driveshaft position is noted at the moment the computer issignalled that the cluster box is centered. Then the distance the drivemember 20 must be driven from center can be determined mathematically bythe computer based upon the geometric dimensions (such as the radius, R,the gear box ratio, etc.) of the drive system. The distance the clusterbox 12 is driven is then controlled by the computer controlling thedegree of rotation of the servomotor's driveshaft.

Sensors at opposite extremes of the center signal the computer if thecluster box 12 has exceeded the normal path, or if, to avoid damage, thecluster box 12 must be stopped from further motion in the presentdirection. It is preferred that the stroke of the present invention bevariable from four to 12 inches.

The drive belt 34, once adjusted in tension by rotating the tensioningpulleys 44 and 46, does not loosen or tighten during the operatingcycle. This is due to the relationship between the curvature of thecurved surface 24 of the support panel 22 and the motion of the drivemember 20. Because the radius of curvature, R, of the curved surface 24is substantially equal to the distance from the curved surface 24 to theaxis of the pivot shafts 16, and because the drive belt between the idlepulleys 40 and 42 and the curved surface stays seated against the curvedsurface 24, the drive belt 34 maintains the same tension during themovement of the drive member 20 from one extreme to the other.

The outer circumferential surfaces of the idle pulleys 40 and 42 thatare closest to the curved surface 24 are spaced slightly from the curvedsurface 24 to permit the drive belt 34 to pass through the spaces. Theclose proximity of the idle pulley surfaces and the curved surface 24prevents slackening of the drive belt 34 during operation, which wouldoccur if the spaces were significantly greater than the thickness of thedrive belt 34.

The tensioning pulleys 44 and 46 have tension adjustment screws 60 and62, respectively, as shown in FIG. 3. Once the opposite ends of thedrive belt are positioned between the tensioning pulleys 44 and 46 andthe clamps 48 and 50, the screws 60 and 62 can be adjusted to change thetension on the drive belt 34. The ends of the screws 60 and 62 contactcurved inner cam surfaces on the tensioning pulleys, which causes slightrotation of the tensioning pulleys upon rotation of the screws 60 and62. Of course, other adjustment mechanisms are contemplated as beingequivalent to the preferred structure.

One advantage of the drive system of the present invention is theability to create a trapezoidal velocity curve with the servomotor.Conventional drive systems, such as a crank and motor, approximatesinusoidal motion, which does not provide slices that are as accuratelypatterned as with the trapezoidal velocity curve. This is becausevariations in workpiece velocity are minimal or nonexistent except atthe extremes of the cycle, whereas with a sinusoidal motion variationsare significant throughout.

The advantage of a trapezoidal velocity curve is most apparent whenslicing a group of food logs, such as those shown in FIG. 5. Because thevelocity of the cluster box is essentially constant during cutting, thefood slices that fall from the cluster box fall onto a substrate, suchas a pizza crust, in an even slice pattern. Without the constantvelocity, the spacing would be uneven, resulting in an uneven slicepattern. Sinusoidal motion of the prior art machines produces a slicepattern with closely spaced slices formed initially, greater spacingbetween the middle slices, and close spacing nearer the end of theslice. Such spacing is more noticeable the longer the stroke. With thepresent invention, slice patterns are significantly improved.

Additionally, the drive system of the present invention is narrower thanconventional drive mechanisms, and this permits several cluster boxes tobe grouped very closely together.

Furthermore, each drive system can be housed in the drive system region2 shown in FIG. 2, which is separated from the food slicing area 6,shown in FIG. 4. This separation allows the drive system parts to bemade of any material, and eliminates the need to clean the drive systemin the same manner as food-contacting parts of the slicing machine.

While certain preferred embodiments of the present invention have beendisclosed in detail, it is to be understood that various modificationsmay be adopted without departing from the spirit of the invention orscope of the following claims.

What is claimed is:
 1. A drive system for a food product slicing machinehaving a frame and an attached workpiece-retaining carriage forreciprocating the food product workpiece retained therein through a pathincluding a cutter, the drive system comprising: (a) a drive memberdrivingly linked to the workpiece-retaining carriage and pivotablymounted to the machine frame about a pivot axis; (b) a support panelmounted to the drive member, the support panel having a circularlycurved surface spaced from the pivot axis a distance substantially equalto a radius of curvature of the curved surface, said curved surfacehaving first and second opposing ends; (c) a first idle pulley rotatablymounted to the machine frame; (d) a second idle pulley rotatably mountedto the machine frame spaced from the first idle pulley, forming a gap;(e) a drive pulley drivingly linked to a rotatably driven shaft of aprime mover; and (f) an elongated, flexible drive means having first andsecond ends, the first drive means end extending from attachment to thedrive member, near the first end of the support panel's curved surface,through the gap between the first and second idle pulleys, around thedrive pulley, through the gap, the second drive means end attached tothe drive member near the second end of the support panel's curvedsurface.
 2. A drive system in accordance with claim 1, wherein the drivemember is rigidly mounted to the workpiece-retaining carriage near afirst drive member end, the support panel is rigidly mounted to thedrive member near a second, opposing drive member end, and the pivotaxis is positioned between the first and second drive member ends.
 3. Adrive system in accordance with claim 1, wherein the elongated, flexibledrive means is a belt.
 4. A drive system in accordance with claim 3,wherein a first belt gap is formed between the curved surface of thesupport panel and a closest peripheral edge of the first idle pulley,and a second belt gap is formed between the curved surface of thesupport panel and a closest peripheral edge of the second idle pulley,said first and second belt gaps being substantially equal to a drivebelt thickness.
 5. A drive system in accordance with claim 3, whereinthe belt has alternating ridges and grooves forming a toothed surface.6. A drive system for a food product slicing machine having a frame andan attached workpiece-retaining carriage for reciprocating the foodproduct workpiece retained therein through a path including a cutter,the drive system comprising: (a) a drive member having a first endrigidly mounted to the workpiece-retaining carriage and a second,opposing end, said drive member being pivotably mounted to the machineframe about a pivot axis positioned between the first and second drivemember ends; (b) a support panel mounted near the second end of thedrive member, the support panel having a circularly curved surfacespaced from the pivot axis a distance substantially equal to a radius ofcurvature of the curved surface, said curved surface having first andsecond opposing ends; (c) a first idle pulley rotatably mounted to themachine frame; (d) a second idle pulley rotatably mounted to the machineframe spaced from the first idle pulley, forming a gap; (e) a drivepulley drivingly linked to a rotatably driven shaft of a prime moverthat is mounted to the machine frame; and (f) an elongated, flexibledrive belt having first and second ends, the first belt end extendingfrom attachment to the drive member, near the first end of the supportpanel's curved surface, through the gap between the first and secondidle pulleys, around the drive pulley, through the gap, the second beltend attached to the drive member near the second end of the supportpanel's curved surface.
 7. A drive system in accordance with claim 6,further comprising a split pivot bushing mounted between the pivot axisand the machine frame.